GSC Sentinel-2 PDGS OCD - Emits - ESA
GSC Sentinel-2 PDGS OCD - Emits - ESA
GSC Sentinel-2 PDGS OCD - Emits - ESA
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<strong>GSC</strong> <strong>Sentinel</strong>-2 <strong>PDGS</strong> <strong>OCD</strong><br />
Issue 1 Revision 2 (draft) - 25.07.2010<br />
GMES-GSEG-EOPG-TN-09-0008<br />
page 278 of 350<br />
‣ DAG function client side, supporting the product-component download activities and<br />
user product reconstruction.<br />
The DAG function server side is strongly coupled to the <strong>PDGS</strong> data management functions<br />
(i.e. the AI and DPC functions) and as such it performs the following activities:<br />
<br />
Retrieve the required product data from the different archives<br />
Trigger the user requested hosted-processing activities<br />
Transmit the retrieved/processed data to the client side<br />
The DAG function client side is focused on the final user activities to get the desired <strong>Sentinel</strong>-<br />
2 image products, as such as the following activities are encompassed within the client:<br />
Connectivity towards the different centres<br />
Hosted-processing user requests management<br />
User-Products retrieval by product components download and subsequent build-up<br />
6.10.1.3 Interfaces to the Front-End Services<br />
To a high level, the users will perform the following operations as part of the data-access<br />
activities:<br />
‣ Product discovery operations based on the catalogued product data;<br />
‣ Subsequently products download operations.<br />
The Front-End Services are responsible of the catalogue of the <strong>Sentinel</strong>-2 product data, being<br />
the MMUS function the one that catalogues all the <strong>Sentinel</strong> production (cf. section 6.11) and<br />
the OLIB function (cf. section 6.12) the function that catalogues the <strong>Sentinel</strong>-2 True Colour<br />
Images. The product catalogue activities will support the Users product discovery requests<br />
including the product pre-visualisation, filter on the metadata, etc.<br />
After selecting the product(s) (through the MMUS or OLIB functions) interested in, The user<br />
will nominally request for the subsequent product download at the user base. The product<br />
download capabilities are responsibility of the DAG function as explained in the previous<br />
sections encapsulating to the user the <strong>PDGS</strong> distributed nature.<br />
Accordingly the DAG client side will interface with the MMUS and OLIB function to receive the<br />
user requests for product download based on the previous data discovery activities performed<br />
by the user. Therefore the DAG client side will implement the download request interface as<br />
defined mainly by the MMUS function.<br />
6.10.2 OPERATION CONSTRAINTS<br />
The DAG function operations must cope with a currently unknown and potentially evolving<br />
number of users of the <strong>Sentinel</strong>-2 production. As such, the function design and architecture<br />
must be able to efficiently use the network resources available and scale according to the<br />
new data communication capabilities.<br />
<strong>ESA</strong> UNCLASSIFIED – For Official Use<br />
© <strong>ESA</strong><br />
The copyright of this document is the property of <strong>ESA</strong>. It is supplied in confidence and shall not be reproduced, copied or<br />
communicated to any third party without written permission from <strong>ESA</strong>.
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